Md.Kausher ahmed Electrical department

Biomedical engineering Code:6875

Lesson declared Medical imaging system

Learning outcomes After finished this lesson student will able to # Say. about CT scan. # Say about The X-Ray Machine. # Say about The Ultrasound Machine.

CT scan Sketch of a CT scanner

Continue,,,,, An X-ray computed tomography (X-ray CT) or computerized axial tomography scan (CAT scan), makes use of computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional (tomographic) images (virtual 'slices') of specific areas of a scanned object, allowing the user to see inside the object without cutting.

Continue,,,,, X-ray computed tomography (X-ray CT) is a technology that uses computer-processed X-rays to produce tomographic images (virtual 'slices') of specific areas of a scanned object, allowing the user to see inside the object without cutting. Digital geometry processing is used to generate a three-dimensional image of the inside of the object from a large series of two-dimensional radiographic images taken around a single axis of rotation

Continue,,,,, Medical imaging is the most common application of X-ray CT. Its cross-sectional images are used for diagnostic and therapeutic purposes in various medical disciplines. The rest of this article discusses medical-imaging X-ray CT; industrial applications of X-ray CT are discussed at industrial computed tomography scanning.

Continue,,,,, As X-ray CT is the most common form of CT in medicine and various other contexts, the term computed tomography alone (or CT) is often used to refer to X-ray CT, although other types exist (such as positron emission tomography [PET] and single-photon emission computed tomography [SPECT]). Older and less preferred terms that also refer to X-ray CT are computed

Continue axial tomography (CAT scan) and computer- aided/assisted tomography. X-ray CT is a form of radiography, although the word "radiography" used alone usually refers, by wide convention, to non-tomographic radiographyCT produces a volume of data that can be manipulated in order to demonstrate various bodily structures based on their ability to block the X-ray beam.

The Ultrasound Machine Although, historically, the images generated were in the axial or transverse plane, perpendicular to the long axis of the body, modern scanners allow this volume of data to be reformatted in various planes or even as volumetric (3D) representations of structures. Although most common in medicine, CT is also used in other fields, such as nondestructive materials testing. Another example is archaeological

Continue,,,,,,,,,, uses such as imaging the contents of sarcophagi. Individuals responsible for performing CT exams are called radiographers or radiologic technologists and are required to be licensed in most states of the USA. Usage of CT has increased dramatically over the last two decades in many countries. An estimated 72 million scans were performed in the United States in 2007.One study estimated

Continue,,,,,,,,,, that as many as 0.4% of current cancers in the United States are due to CTs performed in the past and that this may increase to as high as 1.5 to 2% with 2007 rates of CT usage; however, this estimate is disputed, as there is not a scientific consensus about the existence of damage from low levels of radiation. Kidney problems following intravenous contrast agents may also be a concern in some types of studies.

Diagnostic use

Head Computed tomography of human brain, from base of the skull to top. Taken with intravenous contrast medium.

Continue,,,,,,,,,, Bone reconstructed in 3D

The X-Ray Machine The heart of an X-ray machine is an electrode pair -- a cathode and an anode -- that sits inside a glass vacuum tube. The cathode is a heated filament, like you might find in an older fluorescent lamp. The machine passes current through the filament, heating it up. The heat sputters electrons off of the filament surface. The positively-charged anode, a flat disc made of tungsten, draws the electrons across the tube.

The X-Ray Machine

The voltage difference between the cathode and anode is extremely high, so the electrons fly through the tube with a great deal of force. When a speeding electron collides with a tungsten atom, it knocks loose an electron in one of the atom's lower orbitals. An electron in a higher orbital immediately falls to the lower energy level, releasing its extra energy in the form of a photon. It's a big drop, so the photon has a high energy level -- it is an X-ray photon.

Fig: Cat scanner

Fig: Ct scanner

Fig : The X-Ray Machine

Task # Explain about CT scan. # Explain about The X-Ray Machine. # Explain about The Ultrasound Machine.

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